Definition of «Vaccination»

Vaccination: Injection of a killed microbe in order to
stimulate the immune system against the microbe, thereby preventing disease. Vaccinations,
or immunizations, work by stimulating the immune system, the natural disease-fighting
system of the body. The healthy immune system is able to recognize invading bacteria and
viruses and produce substances (antibodies) to destroy or disable them. Immunizations prepare the immune system to ward off a disease. To immunize against viral diseases, the
virus used in the vaccine has been weakened or killed. To only immunize against bacterial
diseases, it is generally possible to use a small portion of the dead bacteria to
stimulate the formation of antibodies against the whole bacteria. In addition to the
initial immunization process, it has been found that the effectiveness of immunizations
can be improved by periodic repeat injections or "boosters." Also see Vaccines
(in the plural) and Vaccine of a specific type (such Vaccine, Polio).